Piston



W. A. OUBRIDGE PISTON Filed July 27, 1934 Patented Dec. 10, 1935 PATENT .orrlce PISTON William Arthur outrage-country, England Application July 27, 1934, Serial No. 737,292

In Great Britain December 16, 1933 2 Claim. This invention relates to pistons of the light .metal alloy e in which the piston rings, or

certain of them, are mounted in an incast carrier surrounding the upper part of the piston and made of ametal or alloy having greater wear-resisting qualities than that of the piston itself. l

. Where the piston ring carrier is made of grey cast iron the difference between its coefficient of thermal expansion and that of the piston makes it essential to provide some means for preventing the development of relative movement between the carrier and the piston. It is also desirable to provide against the possible risk of the carrier being displaced from the top of the piston by the inertia forces set up by the reciprocating piston even in those cases where the light metal alloy piston and the piston ring carrier have a common coeflicient' of expansion. For example, the piston may be of aluminium alloy with a silicon content of 12% to 14% and the cast iron carrier may be of austenitic structure with a nickel content of 18%to 20%, or a nickel content of 16% and a copper content of 2% to 3%; or a nickel content of 15%, a copper content of 6% and a chromium content of 2.5%; or a manganese content of approximately together with a nickel content of not more than 12% with or without aluminium and/or copper up to 5%. In addition to the use of nickel, and/or copper and manganese, suitable proportions of chromium, molybdenum, vanadium or titanium may be employed to modify the hardness and wear resistance of the material of the piston rimg carrier.

The object of the present'invention is to pro-, vide new or improved methods of and means for locking the carrier to the piston. Z, 1 According to the present invention a flrmtom nection between the piston and the piston ring carrier is obtained by forming the latter with casteilations which when the piston is cast about the carrier extend to and form part of the outer peripheral surface of the piston and eifcctually prevent any tendency toward angular movement of the carrier relatively to the piston. The connection is further secured by means of a locking ring which is inserted in 7 formed around the piston and the castellations of the carrier after the casting process, said ring' by its engagement with both the piston and the carrier p v n ing y tendency for relative movement to take place between the piston and V the carrier in an axial direction.

In the accomp ying drawing, Figure l is a general view of the improved pistonring carrier per se.

Figure 2.is apartsectionalviewofapiston provided with a piston ring carrier in accordance with this invention.

an annular groove V castellations for preventing displacement of said so both sides. 5

After the piston b is cast aboutthe ring an annular groove c is formed in the piston around the castellated portion of the ringa to receive a locking ring it of steel or other suitable mate rial, as shown in Figure 2.

The said can'ier ring may be made either of grey cast iron or of austenitic iron of substantially the compositions above set forth. In the former case it is essential to provide against any slackness that may develop betweenthe car- 15 rier ring and the piston owing to their difierent coeiiicients of expansion, and in the latter case, where the respective coeflicients of expansion of the carrier ring and piston are approximate- 1 alike, it is still necessary to provide against the possible risk of the carrier being displaced from the top of the piston by the inertia forces set up by the rapid reciprocatory motion of the latter. 7

Inbothcaslstheuseofacarrierring of the kind described provides an adequate solution of the diiiicuity, the casteliations a by intimate engagement with the piston, eifectually preventing any tendency for the carrier ring to rotate relatively to the piston, whilst the locking 7 ring d, by its engagement with both the piston and I claim:

1. A piston comprising a cylindrical-light metal alloy casting forming the body thereof, a hard metal band incast around said body to receive piston rings and having castellations extending to and forming partof the outer peripheral surface of said body, and a ring surrounding and interlockingwithsaldbodyandtheonterendsofsaid band.

2. A piston comprising a cylindrical ligl:(t metal alloy-casting forming the body thereof, a hard metal band incast around said body to recelvepiston'Tiacking devices and having castellations extendingtoandfonningpartoftheouterperlpheralsurfaceci'saidbody, andmeansalternately engagingsaidbodyandsaidcastellationsforpreventing displacemmtofsaidband.

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